Introduction

The Tamron AF 90mm f/2.8 SP Di macro is a recent update to the highly popular AF 90mm f/2.8 SP macro.
The lens is a designated Di (Digitally Integrated) lens which refers to an optimized lens
design for image sensors specially regarding chromatic aberrations (CAs). Tamron also improved the
coating of the lens elements to take care of the more pronounced reflections from the image sensor.
The lens belongs to Tamron's SP (Super Performance) line up indicating a
professional grade lens similar to Sigma's EX lenses.
On APS-C DSLRs the field-of-view is equivalent to about 145mm
on full format cameras. The primary application of the lens is, obviously, macro photography
but it's not limited to that - infinity focus is possible.

The optical construction is made of 12 elements in 9 groups without any special elements.
The lens features 9 aperture blades. Typical for most macro lenses the lens provides a
max. magnification of 1:1 at a min. focus distance of 0.29m. The filter size is 55mm.
With a weight of 405g and a size of 72x97mm it is more compact than e.g. the Canon EF 100mm f/2.8 USM macro -
at least a infinity focus. The length of the lens grows substantially when focusing towards
closer distances.

The build quality is very good with an exceptionally smooth but little damped
focus ring. The front element does not rotate so using a polarizer is not problem.
Besides the lens and a softbag the lens package also includes a lens hood but this is really
a strictly optional accessory item because the front element resides deep within the
lens (about 2cm below the front) making it a little hard to clean the lens.

Switching between manual and auto-focus isn't done via a small switch as typical for most lenses
but via a focus clutch mechanism by moving the focus ring back and forth. This can be done in
any focus position. Quite nice actually (Canon & Nikon only. On
Minolta and Pentax DSLRs it is a two step process). On the downside the friction of the mechanism
is quite high so if you pre-focus using AF and switch back to MF you tend to shift the focus setting.
The AF speed is decent for a macro lens.